Specialty Contact LensIndependent guide

Scleral lenses

A scleral lens is a large rigid gas permeable lens that arches completely over the cornea and lands on the sclera, the white of the eye. The space underneath fills with sterile saline, so the eye looks through a smooth layer of fluid rather than through its own irregular surface. That does two things at once — it corrects irregularity that nothing else can, and it keeps the cornea continuously bathed, which is why sclerals are fitted for severe dry eye as well as for corneal disease.

By the Specialty Lens TeamLast reviewed

What makes a scleral different

Every other lens on this site touches the cornea. A scleral lens does not.

It is large — considerably wider than the cornea — and it arches over the whole corneal surface before landing on the sclera, the white of the eye. The gap underneath is filled with sterile saline before the lens goes in, and that fluid stays there while you wear it.

Two consequences follow, and between them they explain every use of the lens:

The eye looks through fluid, not through its own surface. Whatever shape the cornea is — coned, scarred, grafted, rippled after surgery — the optical surface is now the smooth front of the lens with a smooth fluid layer behind it. This is the same tear-lens principle as a corneal rigid lens, taken to its limit, which is why sclerals succeed on corneas too irregular to hold any other lens.

The cornea is continuously bathed. The reservoir does not evaporate and is not blinked away. For an eye whose surface is failing — severe dry eye, graft versus host disease, Sjögren’s, exposure after facial nerve palsy — that sustained contact with fluid is therapeutic in a way drops are not, because drops leave within minutes.

Who scleral lenses suit

  • Advanced keratoconus, particularly where corneal or hybrid lenses no longer fit stably.
  • After a corneal transplant, where the graft surface is regular in itself but sits at a different level from the surrounding cornea.
  • After refractive surgery that healed unevenly.
  • Corneal scarring from injury or infection.
  • Severe dry eye and ocular surface disease, where the goal is as much protecting the surface as correcting vision.
  • Pellucid marginal degeneration and other peripheral thinning disorders, where the irregularity sits too far out for a corneal lens.
  • Anyone who has failed other specialty lenses — this is frequently the lens of last resort, and it frequently works.

Where scleral lenses fall short

  • Handling is the hardest of any lens. Filling with saline, inserting without a bubble, and removing with a plunger all take practice. This is the most common reason a scleral fitting fails, and it is a practical barrier rather than a medical one.
  • Cost. The fitting takes the most chair time of any lens type and the lenses themselves are expensive.
  • Daily consumables. You need preservative-free saline every day, which other lens types do not require.
  • Midday fogging affects some wearers, where the reservoir clouds and vision degrades until the lens is removed, rinsed and refilled.
  • They are not for a regular cornea. If a soft lens or spectacles correct you well, a scleral is a great deal of complexity for no gain.

How the fitting works

Scleral fitting is the most involved in specialty contact lens practice.

  1. Topography, and increasingly scleral profilometry — a map of the white of the eye as well as the cornea, since the sclera is what the lens lands on and it is not symmetrical.
  2. A diagnostic lens, filled and inserted by the fitter.
  3. Settling, then assessment with optical coherence tomography or a slit lamp to measure the clearance between lens and cornea at several points. Too little clearance and the lens touches; too much and oxygen supply suffers.
  4. Landing zone assessment — how the edge meets the sclera, whether it is compressing blood vessels, whether it is lifting anywhere.
  5. Over-refraction, then order.
  6. Teaching, which takes real time: filling, insertion, removal, cleaning, and what to do about bubbles.
  7. Follow-up, repeatedly, because the first lens is rarely the last.

Scleral against the alternatives

Scleral Hybrid Corneal GP Custom soft
Fits very irregular corneas Most reliably Sometimes Sometimes Rarely
Helps severe dry eye Yes No No No
Touches the cornea No Yes Yes Yes
Handling difficulty Highest Moderate Low Lowest
Needs daily saline Yes No No No
Fitting cost Highest Moderate Lowest Moderate
Can dislodge in sport Rarely Rarely Yes Rarely

Questions worth asking at the fitting

  • Is my cornea irregular enough to need a scleral, or would a hybrid do?
  • Is dryness part of my problem, or is this purely about correcting vision?
  • How much teaching time is included for insertion and removal?
  • What saline should I use, and how much will that cost over a year?
  • What is the plan if I get midday fogging?

Common questions

Are scleral lenses comfortable?

Most wearers find them more comfortable than corneal rigid lenses, which surprises people given the size. The reason is that the lens never touches the cornea — the most densely innervated tissue in the body — and its edge rests on the far less sensitive sclera, underneath the eyelid rather than at its path of travel. Comfort problems in a scleral usually indicate a fit that needs adjusting rather than something you have to tolerate.

Do scleral lenses help dry eye?

This is one of the two main reasons they are fitted. Because the lens vaults the cornea, the space underneath holds a reservoir of saline that stays in contact with the eye's surface all day. For severe dry eye and ocular surface disease, that continuous bath can be more effective than drops, which wash away within minutes. It is a mechanical solution to a surface problem.

How hard are scleral lenses to put in?

Harder than any other lens type, and this is the honest barrier. The lens has to be filled with saline and brought to the eye level, without spilling and without trapping a bubble. Most people need a plunger or a stand, and most need real practice before it becomes routine. Fitters expect to spend proper teaching time on it, and you should expect your first attempts to be clumsy.

Are scleral lenses better than hybrids?

Not better — different. A scleral can clear almost any corneal shape and helps a dry ocular surface, which a hybrid cannot do. A hybrid is simpler to handle, cheaper to fit, and sufficient for many people with mild to moderate irregularity. The deciding factors are usually how irregular your cornea is, whether dryness is part of the problem, and how much handling complexity you want.

Hybrid lenses

A rigid centre for sharp optics, a soft skirt for comfort and stability. Mostly fitted for keratoconus and irregular corneas.

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Rigid gas permeable

The sharpest optics available for an irregular cornea, and the most durable lens. The trade-off is adaptation.

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Hybrid vs scleral

Both give rigid optics comfortably. The deciding factors are corneal irregularity, dryness and handling.

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Keratoconus

Every lens option fitted for keratoconus, in the order fitters usually work through them.

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